Polymer films in general, and window films in particular, can be used in many applications to provide performance enhancement to an associated device, material, glazing, or other item. For example, display devices such as plasma displays, cathode ray tubes, and light emitting diode devices can all be enhanced with the incorporation of a polymer film. Films can also be applied to surfaces of other materials, such as shades and blinds, to provide various character enhancements.
One particularly common use of polymer films is as an enhancement layer on a glazing or within a multiple layer glazing panel. Polymer films can be applied to a glazing, for example a window, either at the time of manufacture or anytime thereafter. For example, polymer films can be retrofitted to existing windows by using an adhesive to bond a polymer film directly to the exposed surface of a window. Retrofitted applications are particularly useful for improving the solar transmission characteristics of a window.
The ability to reduce transmission of infrared radiation, and specifically near infrared radiation, can be a particularly desirable characteristic of a polymer film, and particularly for polymer films that are used in architectural applications. Reducing the transmission of infrared radiation can result in the reduction of heat generated by such radiation within an enclosed space.
There are many examples in the polymer arts of compositions and methods that reduce infrared radiation transmission. Included among these is the use of agents that selectively absorb radiation in the infrared region. One effective, known agent is lanthanum hexaboride (LaB6). Lanthanum hexaboride, while an excellent selective absorber of near infrared radiation, is subject to molecular degradation due to commonly encountered environmental conditions, which compromise its infrared absorbing ability.
Further improved compositions and methods are needed to enhance the characteristics of polymer films comprising infrared absorbing agents, and, specifically, polymer films comprising lanthanum hexaboride, so as to impart stability without detrimentally affecting optical qualities.